HIV

HIV is a viral infection that attacks the immune system. This test is done to diagnose HIV infection by detecting the HIV-1 and HIV-2 antibodies in the blood. This is not a screening test as this test does not detect an HIV infection soon after exposure. It is used to detect the antibodies formed after 3 to 12 weeks after exposure.
A negative HIV antibody test usually indicates that a person does not have HIV antibodies. Although in initial few weeks after exposure (window period) the result might be negative. In such cases a repeat testing after few weeks is advised.  Positive result needs to be confirmed with supplemental testing, that is ELISA and PCR test. A positive result for both initial screening and supplemental testing is considered as a definitive diagnosis of HIV infection.